Higher areal storage density for magnetic storage drives can be achieved by decreasing the size of magnetic grains used for magnetic recording media. As grain sizes with a given magnetic anisotropy energy decrease in volume, eventually a stability limit is reached, at which random thermal fluctuations at room temperature result in magnetization reversal and corresponding loss of data reliability.
To avoid the thermal stability limit, materials having higher magnetic anisotropy energy at room temperature can be used to form the magnetic grains of a magnetic stack. However, writing data to these high magnetic anisotropy materials is more difficult and some type of energy assistance may be used to temporarily reduce the magnetic anisotropy energy of the materials while a magnetic write field is applied. For example, one form of energy assisted magnetic recording, referred to as heat assisted magnetic recording (HAMR) involves heating a magnetic medium in synchrony with a writing magnetic field.